--for a skin biopsy to test for small-fiber neuropathy to be done only on the upper extremity, as the majority of small-fiber neuropathy cases are length-dependent--that is, the longer nerve fibers in the legs and feet are affected first. Usually, samples are taken from just above the ankle and the mid-thigh, and also sometimes from the back of the elbow and the gradients compared. If there is also NOT a length-dependent gradient, that also has implications for diagnosis. But the comparisons should be done, as it is possible to have "local", non-systemic nerve damage/axon loss, often from injury, and that would likely show on a skin biopsy as damage to one area but not another. For instance, axon loss in the upper arm, but not in the thigh or calf, would be consistent with nerve injury to the brachial plexus or the cervical spine roots, and in the latter case most likely caused by either acute disc injury or more chronic neural formainal narrowing due to disc herniation/osteophytic bone spur overgrowth.

And, there's also the RSD history to complicate matters.

It would be wonderful if you could post the language used in the imaging reports--we do have people here well versed in that who could provide perspective.